1. Technical Field
Example embodiments relate generally to non-volatile memory devices, and more particularly to a method of determining a default read voltage of a non-volatile memory device and a method of reading data of the non-volatile memory device.
2. Discussion of the Related Art
Memory cells of a non-volatile memory device, such as a flash memory device, may store data by using multiple threshold voltage distributions to represent different logic states of the data. The data stored in the memory cells may be read by checking whether each memory cell is turned on or off when a predetermined read voltage is applied to the memory cell.
While or after the memory cells are programmed to have the threshold voltage distributions, each threshold voltage distribution may widen due to a charge leakage, a program disturb, electrical coupling, a change in temperature, a change in voltage, etc. If the threshold voltage distributions are widened, the data may be inaccurately read. That is, a read failure may occur. Once the read failure occurs, a conventional non-volatile memory device may perform a read retry. Since the read operations are repeatedly performed, a read time may be increased by the read retry.
To reduce the number of read retries, a method of determining a default read voltage of the non-volatile memory device to reduce or minimize read errors according to threshold voltage distribution of memory cells may be desired.